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Test Code CA125 Cancer Antigen 125 (CA 125), Serum, LAB155

Additional Codes




Performing Laboratory

Pathology Laboratory Des Moines, IA

Specimen Requirements

Preferred Container/Tube:  Green or mint-green with gel separator, lithium heparin
Acceptable Container/Tube: Gold-top serum gel tube or plain, red-top tube
Specimen: 1.0 mL of plasma or serum, minimum 0.5 mL
Stability:  Separate from cells ASAP.  Stable 7 days refrigerated.  Preference is to freeze, stable 6 months.

Transport Temperature: Frozen
Collection Instructions: Send specimen frozen in plastic vial.  Avoid repeat freeze/thaw cycles.

Day(s) Test Set Up

Monday - Sunday

Test Classification and CPT Coding


Useful For

CA 125 is a useful tumor marker for evaluating therapy and monitoring disease status in patients under treatment for ovarian cancer. Post-operatively, the level of CA 125 correlates with tumor bulk and is a prognostic indicator of clinical outcome.   It has been reported that patients with levels exceeding 35 U/mL have the highest risk for clinical recurrence.  It has been reported in the literature that prior to a second-look laparotomy, a patient with levels of CA 125 greater than 35 U/mL is very likely to have tumor present at the surgery or to have a future recurrence.  However, a level of CA 125 less than 35 U/mL prior to a second-look operation is not definitive evidence that the patient is free from residual tumor. Levels of CA 125 measured after a second-look operation provides strong indications of clinical outcome.


Measured serially, the levels of CA 125 correspond with disease progression or regression.  The rate of change in CA 125 is also highly prognostic. A rapid decrease in the level of CA 125 indicates a positive response to treatment.  Elevated levels of CA 125 after the third course of primary chemotherapy are predictive of poor outcome.  As a diagnostic tool, the level of CA 125 alone is not sufficient to determine the presence or extent of disease. Preoperative levels of CA 125 in patients with malignant pelvic masses provide no information regarding the histologic grade or diameter of the tumor mass. In postmenopausal women, however, the level of CA 125 in combination with ultrasonography may distinguish benign from malignant pelvic masses.  Patients with certain benign conditions, such as hepatic cirrhosis, acute pancreatitis, endometriosis, pelvic inflammatory disease, menstruation, and first trimester pregnancy, have shown elevated levels of CA 125.  Elevated levels are found in 1 to 2% of healthy donors.